Perhaps you should try some spelling variations:
kho tang » cao tang
hieu van » hieu va, thien van, lieu va
hang doi » hang di, hang loi, huong doi
duc tren » duoc tren, dua tren, duc tien
tu sach » thu sach, su sach, te sach
ky lang » ky nang, ky dang, tay lang
ky tang » ky nang, ky dang, ky trong
nam duc » nam duoc, pham duc, nam thuc
va hang » van hang, va nang, va lang
doi duc » do duc, doi duy, oi duc

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ((ky lang) or (((ky tang) OR (kho tang)))) xa hoi. hieu van nam duc va hang doi duc tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ky lang) OR (((ky tang) OR (kho tang)))) xa hoi. hieu van nam duc va hang doi duc tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ky lang) or (((ky tang) OR (kho tang)))) xa hoi. hieu van nam duc va hang doi duc tren".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ky lang) or (((ky tang) OR (kho tang)))) xa hoi. hieu van nam duc va hang doi duc tren*.